The current invention concerns a device for redirecting electromagnetic beams or ray bundles in the visible spectrum range, in particular laser beams, containing one or more deflecting elements with one or more optically functional interfaces that cause the deflection of a beam or ray bundle striking them by refraction or reflection.
As an example, a multifaceted, rotatable mirror can be employed as a redirecting device of the type mentioned. In addition, the possibility exists of using arrays of cylindrical lenses for redirecting beams. In order to redirect a beam in two mutually orthogonal directions with such arrays, however, two arrays of cylindrical lenses are required for each direction of deviation so that, for a redirection into mutually independent directions, a total of four cylindrical lens arrays would be needed. Both redirecting devices described above, according to the current state of the art, are of complex construction and can be produced only at relatively great expense.
The basic task of the current invention is the creation of a redirecting device of the type mentioned at the beginning with a less complicated and more economical construction.
This is achieved according to the invention by the distinguishing characteristics of Claims 1 through 26. According to the invention, the optically functional interface is bent in such a way that along a first direction, lying essentially in the optically functional interface, the local inclination of the optically functional interface varies continuously, at least segment-wise, relative to a direction lying essentially in the optically functional interface somewhat orthogonal to the first direction. Utilizing the continuous variation of the inclination of the optically functional interface in one direction relative to the direction perpendicular to it, a redirecting device can be realized from such an optically functional interface according to the invention without great expense. Depending on the contact point of a ray on the optically functional interface along a given direction, the ray is redirected through a small or large angle in the directions orthogonal to it.
In one alternative embodiment of the current invention, the one or more deflecting elements have a somewhat rectangular shape with two surfaces facing one another serving as optically functional interfaces. These optically functional interfaces are twisted surfaces that can preferably be formed as surfaces that can be cut at an angle of 45xc2x0 from a concave-convex cylindrical lens with orthogonal alignment of the cylindrical axes. Likewise for surfaces of this type, the local inclination varies continuously, at least segment-wise, along a first axis relative to a direction oriented essentially orthogonal to it. Based on the fact that one is dealing with twisted cylindrical surfaces, it is useful to employ two twisted surfaces facing one another at relative right angles since one can compensate for image distortions in this way.
Preferably, the deflecting element is provided with positioning devices, which are realized either as a displacement device or else as a rotation device. A possibility as displacement device, for example, is a piezoelectric element, which can displace the deflecting element in one or two mutually orthogonal directions. In addition, rotation devices can be employed which can at least partially rotate the deflecting element around an axis standing essentially perpendicular to the optically functional interface. The possibility further exists to combine displacement and rotation devices so that the directions in which the incoming arrays are redirected can be chosen freely.
In a preferred embodiment of the current invention, the optically functional interface is a twisted, preferably propeller-like, surface. In this way, the deflecting element can have a somewhat quadratic shape wherein the surface opposite the optically functional interface is flat. With the preferred propeller-like surface, an infinitesimally small area around the central point of the optically functional interface is parallel to the opposing flat surface of the deflecting element. This has the advantage that in the optically functional interface two lines oriented roughly orthogonal to one another run through the approximate central point, along each of which lines the local inclination of the optically functional interface does not vary in the direction of the line itself, whereas along either of the lines the local inclination of the optically functional surface varies continuously in a direction perpendicular to the respective line. In this way, it is guaranteed that by displacing the deflecting element in a given direction the ray to be deflected is deflected through a more or less sizable angle only in a direction orthogonal to this direction but not in the direction in which deflecting element was displaced. Thus, two displacement devices, which can displace the deflecting element in two mutually orthogonal directions, can bring about the deflection of the ray in two mutually independent directions. Furthermore, by rotation of such a deflecting element according to the invention, one can produce an applicable rotating focus point of a redirected laser beam, particularly advantageous for laser beam welding.
In a preferred embodiment of the current invention, the redirecting device can comprise a number of deflecting elements, which are combined into an array where the individual deflecting elements are each arranged side-by-side, in the same orientation, parallel to one another. Such an arrangement allows the simultaneous redirection of several mutually parallel beams or ray bundles.
In a preferred embodiment of the current invention, the redirecting device comprises one or more deflection modules wherein each of the deflecting components comprises two deflecting elements. Here, the optically functional interfaces of the deflecting elements of each deflection module correspond to each other in such a way that the surfaces can be made to mesh, at least segment-wise. Moreover, all of the deflecting elements can, for example, be shaped identically. It is advantageous to have the deflecting elements so arranged in each deflection module that their optically functional surfaces essentially face each other in the direction of the beam or ray bundle to be deflected, whereby the two deflecting elements can be displaced in mutually opposite or in two mutually orthogonal directions that are oriented essentially parallel to the optically functional surfaces. Such an arrangement offers the advantage that, for deflecting elements not displaced relative to one another and directly facing each other, even extended ray bundles pass through the deflection module formed from the two deflecting elements undeflected or in any case with parallel displacement. Even ray bundles with very large beam cross-section experience no increase in their beam divergence in passing through such a deflection module. Only when the deflecting elements are displaced relative to each other does a deflection come about, for example in a direction orthogonal to the displacement direction, with still no increase in beam divergence.
The deflecting elements can, for example, have the propeller-like surfaces described above. The possibility also exists, however, that the deflecting elements have optically functional interfaces with parabolic convex or parabolic concave shapes facing each other.
The possibility further exists of using arrays of deflecting elements in place of the deflecting element in the deflection modules mentioned, thereby creating the possibility of redirecting beams or ray bundles with even larger cross-sections.
The possibility further exists that the redirecting device comprises two deflection modules, each having two deflecting elements. These deflection modules can then be arranged one after the other in the beam path of the beam or ray bundle to be redirected so that in the first deflection unit a deflection is performed in a first direction and in the second deflection module a deflection in a second direction orthogonal to the first direction. In this way, the deflection of beams in two mutually independent directions can also be separated spatially from one another.
In a preferred embodiment of the current invention, the deflecting elements are made from a material that is at least partially transparent to the wavelengths of the electromagnetic beams or ray bundles to be redirected, such as, for example, quartz or glass. As an alternative to this, the optically functional interface can be provided with a mirror treatment that is at least partially reflective for the wavelengths used in the electromagnetic beams or ray bundles to be redirected, preferably vapor-plated with an appropriate material, such as gold for example, and consequently used for beam deflection by reflection.
A further solution according to the invention envisions that the redirecting device comprises a deflection module consisting of two deflecting elements in which the first deflecting element is realized as a biconvex cylindrical lens and the second deflecting element as a piano-convex cylindrical lens where the flat optically functional interface of the second cylindrical lens essentially faces one of the convex optically functional interfaces of the first cylindrical lens and where the cylindrical axes of the cylindrical lenses are tilted slightly relative to one another. By displacing the deflection module consisting of the two cylindrical lenses, for example in a direction perpendicular to the impinging beam, the beam or the ray bundle can be redirected upward or downward. Based on the fact that three cylindrical surfaces are employed as optically functional interfaces, any image distortions that might arise are corrected.
Further advantages and features of the current invention are clarified using the following description of preferred embodiments with reference to the accompanying figures. In them are shown: